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Area of Polygons/Transcript
Transcript Title text reads: The Mysteries of Life with Tim and Moby Moby rummages through a paper bag. He pulls out a ceramic tile shaped like a parallelogram and shows it to Tim. TIM: No, not that one. Moby reaches into the bag and pulls out a triangle-shaped tile. He beeps. TIM: Not quite. Moby reaches in and pulls out an envelope. TIM: Oh, now, that’s not even a tile! On-screen, a letter appears. Text reads as Tim narrates: Dear Tim and Moby, how do you find the area for shapes like triangles, trapezoids, and parallelograms? From, Dan. TIM: Finding the area of a square or a rectangle is easy. Moby holds up a square tile and a rectangular tile. The rectangle expands to fill the screen. TIM: You just multiply the base times the height. On-screen, the bottom of the rectangle is labeled, base. The left side of the rectangle is labeled, height. An equation appears, reading, Area equals base times height. The base measures 10 centimeters, while the height measures 5 centimeters. TIM: The area of this rectangle is 10 centimeters times 5 centimeters; that’s 50 square centimeters. An equation appears, reading, 10 centimeters times 5 centimeters equals 50 square centimeters. TIM: The area of a parallelogram is also found by multiplying its base by its height, but there’s a little twist. On-screen, a parallelogram fills the screen. An equation appears, reading, Area equals base times height. TIM: The base of a parallelogram is the same as the rectangle's. On-screen, the bottom side of the parallelogram is labeled, base. It measures 10 centimeters. TIM: But the height is the length of the altitude, not one of the sides. To find the altitude, we draw a line perpendicular to the base to the highest point on the shape. On-screen, a dotted line appears inside the parallelogram, stretching from a point on the base to a point on the top side, directly above it. The line is labeled, altitude. It measures 5 centimeters. TIM: The altitude in our parallelogram measures 5 centimeters, so the area of the parallelogram is 50 square centimeters, just like the rectangle. An equation appears, reading, 10 centimeters times 5 centimeters equals 50 square centimeters. Moby holds up a triangular tile piece. Text reads, triangles. TIM: A triangle is half of a parallelogram; so it makes sense that its area would be one-half of its base times its height. The triangular tile expands to fill the screen. The bottom of the triangle is labeled, base. It measures 10 centimeters. A dotted line appears, stretching from the base to the uppermost point of the triangle. The line is labeled, height. It measures 5 centimeters. An equation appears, reading, area equals one-half of the base times height. TIM: If the base of a triangle is 10 centimeters and the height is 5 centimeters, its area is... one-half of 10 is 5, times 5 is… 25 square centimeters. An equation appears, reading, one-half of 10 centimeters times 5 centimeters equals 25 square centimeters. TIM: Got it so far? Moby beeps and holds up a trapezoid tile. It expands to fill the screen. TIM: That funny looking shape is a trapezoid. It has 2 bases, and an altitude like the parallelogram. On-screen, the top side of the trapezoid is labeled, base a. The longer base at the bottom of the trapezoid is labeled, base b. A dotted line appears between base b, and base a. The dotted line is labeled, altitude. TIM: You can spot the bases because they're the ones that are parallel to each other. On-screen, base a, and base b, are highlighted, demonstrating that they are parallel to each other. TIM: To find the area of a trapezoid, we have to add its 2 bases together, and multiply that amount by one-half the trapezoid's height. An equation appears, reading, area equals one-half of the height, times the sum of bases A, and B. Base A, measures 8 centimeters; base B, measures 10 centimeters, and the altitude measures 6 centimeters. TIM: For our trapezoid, the area is one-half of 6; that's 3, times the sum of 8 and 10. 3 times 18 is 54, and our area is 54 square centimeters! An equation appears, reading, one-half of 6 centimeters times the sum of 8 centimeters and 10 centimeters equals 54 square centimeters. TIM: Some of these shapes may look a little intimidating, but once you know the formulas, finding their areas is pretty easy! Moby beeps. He has painted the area formulas on the wall. TIM: Uh, yeah, writing them down's a good idea… but I would use a notebook or something. Moby beeps. Category:BrainPOP Transcripts Category:BrainPOP Math Transcripts